(a) Field of the Invention
The present invention relates to an apparatus for exchanging a so called casting nozzle and compressively holding an exchanged casting nozzle against a device for controlling the rate of flow of molten metal such as a teeming nozzle or a sliding nozzle plate. The casting nozzle may be an immersion nozzle, a long nozzle that is provided at the bottom of a molten metal container or a refractory member of a sliding nozzle apparatus employed for preventing metal from oxidation and trapping-in of non-metallic inclusions.
(b) Description of the Prior Art
Casting nozzles are required to be frequently changed or replaced with new ones since they are held in direct contact with the flowing molten metal and hence tend to be melted, broken, or otherwise damaged. The casting nozzles should be replaced in a short period of time so as not to increase the downtime. The replacing process is burdensome on the worker since it has to be carried out at high temperature.
When connecting the casting nozzle to the base of a nozzle device, e.g., when coupling an immersion nozzle to the lower nozzle of a sliding nozzle device, a certain pressure must be applied to the nozzle in order to prevent the molten metal from leaking or air from entering the molten metal.
One conventional casting nozzle changer designed to meet the above requirements is disclosed in Japanese Utility Model Publication No. 58-4907. The disclosed nozzle changing apparatus includes an attachment fixed to a slide table holder and having rail grooves and a lower nozzle receiver having horizontal projections fitted slidably in the rail grooves. Two lower nozzles are horizontally slidable through the above interfitting mechanism. One of the lower nozzles is held in intimate fitting contact with the slide table of the sliding nozzle device by means of a wedge-shaped cotter wedged between the rail groove and the projection fitted therein, and the other lower nozzle is freely suspended from the attachment, there being a cotter removing plate between the lower nozzles. The old lower nozzle can be replaced with the new lower nozzle by pushing the new lower nozzle with a piston.
In the conventional practice for changing the lower nozzles, the cotter removing plate is required to be inserted from behind since the lower nozzle should be held in intimate fitting contact with the sliding nozzle slide table when wedging the wedge-shaped cotter with the new lower nozzle held in the fitting position. Therefore, manual labor is needed in a high-temperature environment, using auxiliary tools in wedging the wedge-shaped cotter or attaching and detaching the cotter removing plate.
It has been difficult to adjust or establish the required amount of forces to compressively hold the lower nozzle only with the cotter having a fixed thickness. Consequently, the lower nozzle has not been held in intimate fitting contact with the slide table under an appropriate pressure, and a long period of time has been needed for the operation.